Friends and Family betas get rid of massive bugs and issues. Closed betas deal with smaller bugs and issues. Open betas are for stress testing the servers once everything is fairly stable and mostly bug free, to see how the system responds to a large load. If you open beta'd a game that didn't have most of the bugs ironed out, do you realize what that would do to the stability? Thought not.

Feedback is only a small portion of beta testing. Developers gather tons and tons of data from people just playing. However, it also costs money to have servers online for play. It'd be a massive (and I do mean massive) waste of money to have an open beta this early in development.

Invites will be worldwide regardless of the post only being on US forums. Media figures in EU and US received their invites very close to one another. As far as public invites goes, people suspect they have not gone out just yet. No one has been posting or replying to posts regarding getting beta keys. Obv the argument is that they are playing already. To that, there was an update on the current number of players on the beta in open games. As of right now there's only 58 players listed doing public games across all the quest brackets. I'd expect the number to be much higher if beta invites were flying off the proverbial shelves, even if most people opt to check it out on single player (It's pretty much just the same people doing Skeleton King runs on repeat.) So people are still speculating that the beta invites are a little sluggish.